Mn Toxicity Differentially Affects Physiological and Biochemical Features in Highbush Blueberry (Vaccinium corymbosum L.) Cultivars

Abstract

Manganese (Mn) is an essential micronutrient for plants; however, in excess, it can have negative effects on their physiological and biochemical characteristics. We evaluate photosynthetic performance, antioxidant activity, and organic acid exudations to clarify the mechanisms involved in highbush blueberry (Vaccinium corymbosum L.) under Mn excess. One-year-old plants of V. corymbosum cultivars (Legacy, Brigitta, and Bluegold) were grown in hydroponic solution with 2, 10, 50, 250, 500, and 1000 μM of Mn treatments for 25 days. Plant growth as shoot and root biomass, Mn content, photosynthetic performance [photochemical efficiency of PSII, CO 2 assimilation, and stomatal conductance (g s)], lipid peroxidation, radical scavenging activity, superoxide dismutase activity, and organic acid exudations were analyzed. Mn excess triggered detrimental effects in terms of plant growth, photochemical efficiency, and CO 2 assimilation, as well as in biochemical features in V. corymbosum cultivars. Despite Legacy decreasing its photosynthesis, plant growth was maintained throughout the experiment; by contrast, Brigitta maintained photosynthesis and growth despite the decrease in stomatal conductance (g s). Meanwhile, Bluegold presented the lowest level in net photosynthesis and photochemical processes and an increase in lipid peroxidation. Oxalate and citrate were the most important organic acid anions in Legacy and Brigitta, gradually increasing their concentration with the enhancement of Mn doses. Our study demonstrated that Mn excess negatively and differently affects the physiological and biochemical features of V. corymbosum cultivars, with Legacy and Brigitta being Mn-resistant and Bluegold Mn-sensitive.

Combined Effects of CaCO3 and the Proportion of N-NH4+ Among the Total Applied Inorganic N on the Growth and Mineral Uptake of Rabbiteye Blueberry

“…Those researchers also showed that the increased Mn concentration in the soil solution was accompanied by increased concentrations of oxalate and citrate in the root system. It was suggested that this physiological response could be a possible mechanism for buffering and reducing the high Mn 2+ concentration (Millaleo et al 2020).…”

Soil and Plant Analyses to Diagnose Hop Fields Irregular Growth

“…Mn toxicity can manifest in plants by the reduction of biomass and early leaf senescence through biochemical disorders and, in particular, by damage of the photosynthetic system (Millaleo et al 2010(Millaleo et al , 2019. In this study, leaf Mn concentrations above 200 mg kg −1 were often recorded, mostly on plots of weak plant vigour (> 500 mg kg −1 at harvest in plot 1).…”

“…Toxic products, such as ethanol, lactic acid, acetaldehyde, aliphatic acids and cyanogenic compounds, are also produced under reduction conditions (Parent et al 2008;Pezeshki and DeLaune 2012). The accumulation of these compounds along with the increased available forms of Fe and Mn can have deleterious effects on plants (Millaleo et al 2010(Millaleo et al , 2019Pezeshki and DeLaune 2012). The effects of flooding on plants can be diverse and may include deficiency of some and/or toxicity of other nutrients (Stieger and Feller 1994;Pezeshki and DeLaune 2012) and reduction in photosynthesis and biomass accumulation (George et al 2012;Sparrow and Uren 2014).…”

Revisiting mycorrhizal dogmas: Are mycorrhizas really functioning as they are widely believed to do?

“…First, Soudzilovskaia et al (2020) acknowledge that data on ericoid mycorrhizal vegetation were unreliable. Second, data for most of the southern hemisphere were absent for ericoid mycorrhizal plants, with a bias toward higher latitude ericaceous species or species of horticultural value (Vaccinium species) (Hashem, 1995;Kula et al, 2018;Millaleo et al, 2020). Dominance of ericoid mycorrhizas associated with a very small number of Ericaceae might be due to a range of plant traits, rather than demonstrated competitive advantage of ericoid mycorrhizal fungi.…”

“…However, some Ericaceae, for example, Vaccinium corymbosum (highbush blueberry), exhibit high leaf [Mn] (Millaleo et al, 2020) which is typically associated with a carboxylatereleasing P-acquisition strategy (Lambers et al, 2015). Carboxylate release in some Ericaceae might therefore account for the large variability in leaf [Mn] (Bouwens and Longin, 1979;Pillon et al, 2018) and often high leaf [Mn] (Korcak, 1987;Wojtuń et al, 2017;Kula et al, 2018) in Ericaceae.…”